Crude petroleum oils often contain or generate hydrogen sulfide (H2S) during handling, storage and transportation, which can be corrosive and/or lethal to workers. Thus, H2S scavengers (e.g., triazine compounds) are frequently added to crude oil to suppress H2S evolution during transport to avoid exposure of personnel involved with overland or waterborne shipping. Most commercial H2S scavengers are based on amines, including ethanolamines. Unfortunately, these amines can be extremely corrosive to refinery equipment. During desalting and subsequent atmospheric crude oil distillation, these amines can act as chloride ion transporters which are active corrosion agents in the distillation tower trays, top pump around (TPA) exchangers, the overhead vapor line and condensers. Corrosion rates of 2000 to 5000 mpy in naptha draw line and distillation tower trays have been commonly observed.
Quantitating the molecular species and concentrations of these H2S scavenging amines is important to refiners because even low ppm levels of certain amine species can significantly affect the behavior of the crude oil in desalting and atmospheric distillation units. Significant concentration of amines present in the oil can occur during refining, such that an amine level in the low ppm (or even sub-ppm) range can result in an amine level exceeding 100 ppm in the overhead water stream of a refinery atmospheric distillation tower.
Current methods lack proper sensitivity to detect amines, are too labor intensive and take too long to complete, often causing delays in the refining of a given batch of crude oil. Thus, it is essential to develop an accurate and precise method for rapidly (<6 hours) identifying and quantitating amine species in crude oil samples at levels less than 10 ppm.